/**
 * Created by shushi on 16/3/26.
 */

function GetSlideAngle(dx, dy) {
    return Math.atan2(dy, dx) * 180 / Math.PI;
}

//根据起点和终点返回方向 1：向上，2：向下，3：向左，4：向右,0：未滑动
function GetSlideDirection(startX, startY, endX, endY) {
    var dy = startY - endY;
    var dx = endX - startX;
    var result = 0;

    //如果滑动距离太短
    if(Math.abs(dx) < 2 && Math.abs(dy) < 2) {
        return result;
    }

    var angle = GetSlideAngle(dx, dy);
    if(angle >= -45 && angle < 45) {
        result = 4;
    }else if (angle >= 45 && angle < 135) {
        result = 1;
    }else if (angle >= -135 && angle < -45) {
        result = 2;
    }
    else if ((angle >= 135 && angle <= 180) || (angle >= -180 && angle < -135)) {
        result = 3;
    }

    return result;
}

//滑动处理
var startX, startY;
document.addEventListener('touchstart',function (ev) {
    startX = ev.touches[0].pageX;
    startY = ev.touches[0].pageY;
}, false);
document.addEventListener('touchend',function (ev) {
    var endX, endY;
    endX = ev.changedTouches[0].pageX;
    endY = ev.changedTouches[0].pageY;
    var direction = GetSlideDirection(startX, startY, endX, endY);
    if($("#lightboxOverlay").is(":hidden")){
        document.body.style.overflow='';
    }else {
        document.body.style.overflow='hidden';
        switch(direction) {
            case 0:
                break;
            case 1:
                $('.lb-prev').click();
                break;
            case 2:
                $('.lb-next').click();
                break;
            case 3:
                break;
            case 4:
                break;
            default:
        }
    }
}, false);